Unit Converter
Updated Formulas shown
Pick a quantity, choose the two units and type in either box. The answer updates instantly, with tape-measure fractions for lengths and a list of the same value in every other unit.
Formula: inches = centimeters ÷ 2.54 (exact)
Common values: centimeters → inches
| centimeters | inches |
|---|---|
| 0.393701 in≈ 3/8″ | |
| 0.787402 in≈ 13/16″ | |
| 1.1811 in≈ 1 3/16″ | |
| 1.9685 in≈ 1 15/16″ | |
| 3.93701 in≈ 3 15/16″ | |
| 7.87402 in≈ 7 7/8″ | |
| 9.84252 in≈ 9 13/16″ | |
| 19.685 in≈ 19 11/16″ | |
| 39.3701 in≈ 39 3/8″ | |
| 98.4252 in≈ 98 7/16″ | |
| 196.85 in≈ 196 7/8″ | |
| 393.701 in≈ 393 11/16″ |
10 cm in every length unit
- 100 mm
- 0.1 m
- 0.0001 km
- 3.93701 in
- 0.328084 ft
- 0.109361 yd
- 0.0000621371 mi
- 3,937.01 mil
- 100,000 µm
- 0.0000539957 nmi
How to use the unit converter
- Choose a quantity — length, area, volume, weight, temperature and so on.
- Pick the unit you have on the left and the unit you want on the right. The swap button flips them.
- Type a number in either box. Lengths accept fractions and feet-and-inches (5'9", 3 1/2).
- Set the decimals you need, then copy the result or a share link.
Conversion factors (NIST SP 811)
Each unit is stored as its exact value in the SI base unit, so any pair converts with a single ratio. "Exact" factors are definitions (1 in = 25.4 mm; 1 lb = 0.45359237 kg; 1 US gal = 231 in³); "conventional" ones such as inches of mercury are fixed reference values.
Length
| unit | symbol | in m | exact? |
|---|---|---|---|
| millimeter | mm | 0.001 | exact |
| centimeter | cm | 0.01 | exact |
| meter | m | 1 | exact |
| kilometer | km | 1,000 | exact |
| inch | in | 0.0254 | exact |
| foot | ft | 0.3048 | exact |
| yard | yd | 0.9144 | exact |
| mile | mi | 1,609.344 | exact |
| mil (thou) (1/1000 inch — plastic sheeting and coating thickness) | mil | 2.54 × 10⁻⁵ | exact |
| micrometer | µm | 1 × 10⁻⁶ | exact |
| nautical mile | nmi | 1,852 | exact |
Area
| unit | symbol | in m² | exact? |
|---|---|---|---|
| square millimeter | mm² | 1 × 10⁻⁶ | exact |
| square centimeter | cm² | 1 × 10⁻⁴ | exact |
| square meter | m² | 1 | exact |
| hectare | ha | 10,000 | exact |
| square kilometer | km² | 1,000,000 | exact |
| square inch | in² | 6.4516 × 10⁻⁴ | exact |
| square foot | ft² | 0.09290304 | exact |
| square yard | yd² | 0.83612736 | exact |
| acre (international acre = 43,560 ft²) | ac | 4,046.856422399999 | exact |
| square mile | mi² | 2,589,988.110336 | exact |
Volume
| unit | symbol | in m³ | exact? |
|---|---|---|---|
| milliliter | mL | 1 × 10⁻⁶ | exact |
| liter | L | 0.001 | exact |
| cubic meter | m³ | 1 | exact |
| teaspoon (US customary) | tsp | 4.92892159375 × 10⁻⁶ | exact |
| tablespoon (US customary) | tbsp | 1.47867647812 × 10⁻⁵ | exact |
| fluid ounce (US) | fl oz | 2.95735295625 × 10⁻⁵ | exact |
| cup (US customary cup = 8 US fl oz) | cup | 2.365882365 × 10⁻⁴ | exact |
| cup (US legal) (240 mL, used on US nutrition labels) | cup (legal) | 2.4 × 10⁻⁴ | exact |
| metric cup (250 mL (Canada, Australia, NZ)) | cup (metric) | 2.5 × 10⁻⁴ | exact |
| pint (US liquid) | pt | 4.73176473 × 10⁻⁴ | exact |
| quart (US liquid) | qt | 9.46352946 × 10⁻⁴ | exact |
| gallon (US liquid gallon = 231 in³) | gal | 0.003785411784 | exact |
| cubic inch | in³ | 1.6387064 × 10⁻⁵ | exact |
| cubic foot | ft³ | 0.028316846592 | exact |
| cubic yard | yd³ | 0.764554857984 | exact |
| imperial gallon (UK gallon = 4.54609 L) | imp gal | 0.00454609 | exact |
| imperial fluid ounce (UK) | imp fl oz | 2.84130625 × 10⁻⁵ | exact |
Weight / mass
| unit | symbol | in kg | exact? |
|---|---|---|---|
| milligram | mg | 1 × 10⁻⁶ | exact |
| gram | g | 0.001 | exact |
| kilogram | kg | 1 | exact |
| metric ton (tonne) | t | 1,000 | exact |
| ounce (avoirdupois) | oz | 0.028349523125 | exact |
| pound (avoirdupois) | lb | 0.45359237 | exact |
| stone (14 lb (UK, Ireland)) | st | 6.35029318 | exact |
| short ton (US) (2,000 lb) | ton | 907.18474 | exact |
| long ton (UK) (2,240 lb) | long ton | 1,016.0469088 | exact |
Speed
| unit | symbol | in m/s | exact? |
|---|---|---|---|
| meter per second | m/s | 1 | exact |
| kilometer per hour | km/h | 0.277777777778 | exact |
| mile per hour | mph | 0.44704 | exact |
| knot | kn | 0.514444444444 | exact |
| foot per second | ft/s | 0.3048 | exact |
| foot per minute (HVAC duct air velocity) | ft/min | 0.00508 | exact |
Pressure
| unit | symbol | in Pa | exact? |
|---|---|---|---|
| pascal | Pa | 1 | exact |
| kilopascal | kPa | 1,000 | exact |
| megapascal | MPa | 1,000,000 | exact |
| bar | bar | 100,000 | exact |
| millibar | mbar | 100 | exact |
| pound per square inch | psi | 6,894.757293168361 | exact |
| pound per square foot (roof snow and floor live loads) | psf | 47.880258980336 | exact |
| standard atmosphere | atm | 101,325 | exact |
| millimeter of mercury (conventional) | mmHg | 133.322387415 | conventional |
| inch of mercury (conventional) | inHg | 3,386.388640341 | conventional |
| inch of water (conventional — HVAC static pressure, gas manifold pressure) | in H₂O | 249.08891 | conventional |
Energy
| unit | symbol | in J | exact? |
|---|---|---|---|
| joule | J | 1 | exact |
| kilojoule | kJ | 1,000 | exact |
| megajoule | MJ | 1,000,000 | exact |
| calorie (thermochemical) | cal | 4.184 | exact |
| kilocalorie (food Calorie) (thermochemical) | kcal | 4,184 | exact |
| watt-hour | Wh | 3,600 | exact |
| kilowatt-hour | kWh | 3,600,000 | exact |
| British thermal unit (International Table) | BTU | 1,055.05585262 | exact |
| therm (US) (US therm = 100,000 BTU (59 °F), NIST SP 811) | thm | 105,480,400 | conventional |
| foot-pound | ft·lbf | 1.355817948331 | exact |
Power
| unit | symbol | in W | exact? |
|---|---|---|---|
| watt | W | 1 | exact |
| kilowatt | kW | 1,000 | exact |
| megawatt | MW | 1,000,000 | exact |
| horsepower (mechanical, 550 ft·lbf/s) | hp | 745.69987158227 | exact |
| metric horsepower (75 kgf·m/s (PS, CV, ch)) | PS | 735.49875 | exact |
| BTU per hour | BTU/h | 0.293071070172 | exact |
| ton of refrigeration (12,000 BTU/h) | ton (AC) | 3,516.852842066667 | exact |
| kilocalorie per hour | kcal/h | 1.162222222222 | exact |
Data size
| unit | symbol | in B | exact? |
|---|---|---|---|
| bit | bit | 0.125 | exact |
| byte | B | 1 | exact |
| kilobyte | kB | 1,000 | exact |
| megabyte | MB | 1,000,000 | exact |
| gigabyte | GB | 1 × 10⁹ | exact |
| terabyte | TB | 1 × 10¹² | exact |
| petabyte | PB | 1 × 10¹⁵ | exact |
| kibibyte | KiB | 1,024 | exact |
| mebibyte | MiB | 1,048,576 | exact |
| gibibyte | GiB | 1.073741824 × 10⁹ | exact |
| tebibyte | TiB | 1.09951162778 × 10¹² | exact |
| megabit | Mb | 125,000 | exact |
| gigabit | Gb | 125,000,000 | exact |
Temperature and fuel economy
These scales aren't a single multiplication. °F = °C × 9/5 + 32; K = °C + 273.15; °R = °F + 459.67. Fuel economy flips between distance-per-fuel and fuel-per-distance: L/100 km = 235.215 ÷ US mpg = 282.481 ÷ UK mpg.
Popular conversions
Length
Area
Volume
Weight / mass
Temperature
Speed
Pressure
Energy
Power
Fuel economy
Data size
Frequently asked questions
Where do the conversion factors come from?
NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B. Most factors (inch, foot, pound, gallon, BTU) are exact by definition.
Can I type feet and inches?
Yes. In any length unit you can type 5'9", 5 ft 9 in, 3 1/2 or 7/8 — the converter turns it into the selected unit.
Which gallon and cup are used?
US liquid gallon (231 in³) and US customary cup (8 US fl oz = 236.59 mL) by default. Imperial gallons, UK fluid ounces, the 240 mL US legal cup and the 250 mL metric cup are in the unit menu.
Does anything get uploaded?
No. Every conversion runs in your browser; the share link only stores the numbers in the URL.
Your business here? Sponsor this calculator from $13/week. See placements
Estimates only. Check quantities with your supplier or contractor before ordering.